From what I have read on this site the Greddy turbo kit is a well put together kit and is a pretty good buy. And the only downside of the kit is the internal waste gate.
My friend came up with an idea about welding the internal wastegate off or closed and putting your own external one in. Would there be any benefit to doing this or is it not worth the time and effort

Its just a thought and nothing that I have gone into to much depth about. I just thought that I should ask you guys who have more knowledge on this subject than i do.

 

his idea won't work, i promise, b/c i've researched it

 

yes, it's doable. a lot of Garrett/AiResearch T3 housings are 5 bolt config with an internal wastegate and use a blocker plate in place of the flapper valve housing to accomodate an external wastegate setup.

just need to find a welder who can weld up cast iron... hard to find someone who's truly competent, tho.

look up information on mitsubishi turbines. DSM guys are very familiar with them, and may already have housings that are designed for external wastegates. a bit hard to find, as many DSM owners swap over to a Garrett style turbine instead as the parts are more readily available.